High-pressure behavior of the ternary bismuth oxides Bi2Al4O9, Bi2Ga4O9 and Bi2Mn4O10

The high-pressure behavior of Bi2Al4O9, Bi2Mn4O10 and Bi2Ga4O9 was investigated by in situ powder synchrotron X-ray diffraction. Pressures up to 35 GPa were generated using the diamond anvil cell technique. complementary data of the pressure dependence of Bi2Ga4O9 were obtained by density functional theory-based model calculations. Bi2Al4O9 and Bi2Mn4O10 are structurally stable to the highest pressures obtained. In contrast, a reversible phase transition is observed in Bi2Ga4O9 at approximately 16 GPa. A fit of a 3rd-order Birch-Murnaghan equation of state to the p-V data results in V-0 = 356.93(9) angstrom(3), B-0 = 122(2) GPa and B' = 4.9(3) for Bi2Al4O9; V-0 = 372.27(1) angstrom(3), B-0 = 138(2) GPa and B' = 4.2(2) for Bi2Mn4O10; and V-0 = 388.63(3) angstrom(3), B-0 = 102(8) GPa and B' = 3.8(2) for Bi2Ga4O9. The most compressible axis is the a axis for all the compounds. This behavior can be rationalized in terms of the inflexible polyhedra connections parallel to the b and c axes. (C) 2009 Elsevier Inc. All rights reserved.